This application claims priority to EP/01108759.0, filed Apr. 6, 2001 under the European Patent Convention and which is incorporated by reference herein in its entirety.
The present invention relates to a process for producing a turbine blade or vane, and more specifically for producing a turbine blade or vane in for a gas turbine engine.
The subject matter of the present invention relates to a process for producing a turbine blade or vane, which has at least one chamber and at least one inlet for applying a cooling medium to the chamber, at least one inlet running at an angle with respect to a longitudinal axis of the turbine blade or vane. It also relates to a turbine blade or vane, in particular for a gas turbine, which has at least one chamber and at least one inlet for applying a cooling medium to the chamber.
A process of manufacturing a turbine blade or vane of are described in U.S. Pat. No. 5,599,166 (""166). In the ""166 patent the described turbine blade or vane has two chambers which are separate from one another, run in meandering form and are each connected to an inlet for applying a coolant. The two inlets run substantially parallel to the longitudinal axis of the turbine blade or vane.
U.S. Pat. No. 5,413,458 (""458) describes another turbine blade or vane, which likewise has at least one chamber for applying a cooling medium. The cooling medium of the ""458 patent is in this case supplied in a direction which is likewise substantially parallel to the longitudinal axis of the turbine blade or vane.
A drawback of the known prior art turbine blades or vanes and production processes is the forced fixing of the direction of the inlet. The turbine blades or vanes generally have an airfoil profile, around which a medium passing through the turbine flows. A platform is used to fix the blade or vane to a housing or a rotor. In the known turbine blades or vanes, the cooling medium must first of all flow through the platform before entering the airfoil profile. This means that the platform and the airfoil profile always have to be cooled with the same cooling medium, in particular with a cooling medium which is at the same pressure and the same temperature. Targeted cooling of relatively highly stressed parts of the turbine blade or vane is not possible.
Therefore, it is an object of the present invention to provide a process for producing a turbine blade or vane and a turbine blade or vane itself which allow targeted application of a cooling medium.
According to the invention, this object is achieved, in a process of the type described in the introduction, by the fact that, to form the inlet, a core with a projection is used, and the projection is arranged at a distance from a mold, so that the inlet of the turbine blade or vane is closed after removal from the mold, and in that machining is carried out in order to open up the inlet. In the turbine blade or vane according to the invention, it is provided that the inlet runs at an angle with respect to a longitudinal axis of the turbine blade or vane and runs substantially parallel to a direction of flow of a medium through the turbine.
The core or cores used to produce the turbine blade or vane is/are, as previously described, inserted into and held in the mold. The cores are not supported in the mold by means of the projection. Therefore, the cores can move during the casting operation, as is the case in the known processes. The core position is not influenced by contact between the projection and the mold.
The invention alternatively also provides an inlet running substantially parallel to the longitudinal axis of the turbine blade or vane. The inlet is provided which is arranged at an angle to the longitudinal axis and runs substantially parallel to a direction of flow of the medium through the turbine. This inlet allows targeted application of a cooling medium to highly stressed parts of the turbine blade or vane.
Advantageous configurations and refinements will emerge from the dependent claims.
In the process according to the invention, a second inlet is preferably provided substantially parallel to the longitudinal axis of the turbine blade or vane. The two inlets can then be acted on by different cooling media. This difference may reside in particular in the pressure and/or temperature of the coolant supplied in each case. Therefore, the result is targeted, highly efficient cooling of individual parts of the turbine blade or vane.
It is possible to provide a plurality of projections and, accordingly, a plurality of inlets of this type. The inlets may be arranged on a front edge, a rear edge or both edges of the turbine blade or vane. The targeted arrangement allows optimum cooling of the turbine blade or vane.
According to an advantageous configuration, the inlet which runs at an angle to the longitudinal axis is of tapered design, and more specifically conical. It then has a relatively large cross section at it opening. Therefore, the cooling medium can be passed to the inlet at relatively low pressure and is compressed as it flows in. The inlet is designed in such a way that flow losses are minimized.
The inlet running perpendicular to the longitudinal axis of the turbine blade or vane means that there is sufficient space available. There is no need for a complicated arrangement, which weakens the material, of the two inlets approximately parallel to the longitudinal axis of the turbine blade or vane.
The inlet running in the axial direction is advantageously arranged between a platform and an airfoil profile of the turbine blade or vane. Therefore, the cooling medium which is supplied via this inlet can pass directly into chambers of the airfoil profile. Then, the second inlet, which runs substantially parallel to the longitudinal axis, is used to cool the platform.
The division of the cooling medium, which is provided for according to the invention, is advantageous in particular in the case of a turbine blade or vane which has at least two chambers. The first chamber is then in communication with the first inlet and the second chamber is in communication with the second inlet. In this case, the first chamber is advantageously arranged in the region of a front edge of the turbine blade or vane.
This chamber arranged in the region of the front edge generally has a higher demand for cooling than the second chamber. If the front edge is provided with openings through which the cooling medium can escape, it is also necessary to apply a cooling medium which is at a higher pressure. The reason for this is that the cooling medium, to flow out of the first chamber, has to overcome the jet pressure of the medium flowing through the turbine. According to the invention, the first chamber can now be acted on by a cooling medium which is at a higher pressure than that for the second chamber, via the first inlet. Therefore, this first chamber can deliberately be cooled more extensively. This level of cooling is not necessary for the second chamber. Therefore, the consumption of cooling medium can be optimized, and, as a result, the overall efficiency can be increased. As an alternative or in addition, targeted cooling of the rear edge is also possible.